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Abstract The weakly electric brown ghost knifefish (Apteronotus leptorhynchus) exhibits a pronounced sexual dimorphism in its electric behavior—males discharge at higher frequencies than females, with little overlap between the sexes. The frequency of these electric organ discharges is controlled by the frequency of the synchronized oscillations of the medullary pacemaker nucleus. Previous studies have suggested that sex-specific differences in the morphology and gene expression pattern of the astrocytic syncytium that envelopes the pacemaking neural network cause differences in its capacity to buffer the extracellular concentration of K⁺. This change in the K⁺buffering capacity affects the K⁺equilibrium potential of the neurons constituting the neural network, which in turn modulates the frequency of the pacemaker nucleus. In the present study, we have tested a critical element of this hypothesis by examining whether, and how, changes in the extracellular K⁺concentration influence the frequency of the pacemaker nucleus oscillations. By using an in vitro preparation of the pacemaker nucleus, the results of this investigation demonstrate that exposure of this nucleus to acutely increased/decreased concentrations of K⁺in the perfusate (while maintaining osmolarity) leads to concentration-dependent increases/decreases in the frequency of the synchronized oscillations generated by the pacemaker nucleus. 

Abstract Signal analysis plays a preeminent role in neuroethological research. Traditionally, signal identification has been based on pre-defined signal (sub-)types, thus being subject to the investigator’s bias. To address this deficiency, we have developed a supervised learning algorithm for the detection of subtypes of chirps—frequency/amplitude modulations of the electric organ discharge that are generated predominantly during electric interactions of individuals of the weakly electric fishApteronotus leptorhynchus. This machine learning paradigm can learn, from a ‘ground truth’ data set, a function that assigns proper outputs (here: time instances of chirps and associated chirp types) to inputs (here: time-series frequency and amplitude data). By employing this artificial intelligence approach, we have validated previous classifications of chirps into different types and shown that further differentiation into subtypes is possible. This demonstration of its superiority compared to traditional methods might serve as proof-of-principle of the suitability of the supervised machine learning paradigm for a broad range of signals to be analyzed in neuroethology. 

Abstract Bees are known for their ability to forage with high efficiency. One of their strategies to avoid unproductive foraging is to be at the food source at the right time of the day. Approximately one hundred years ago, researchers discovered that honeybees have a remarkable time memory, which they use for optimizing foraging. Ingeborg Beling was the first to examine this time memory experimentally. In her doctoral thesis, completed under the mentorship of Karl von Frisch in 1929, she systematically examined the capability of honeybees to remember specific times of the day at which they had been trained to appear at a feeding station. Beling was a pioneer in chronobiology, as she described the basic characteristics of the circadian clock on which the honeybee's time memory is based. Unfortunately, after a few years of extremely productive research, she ended her scientific career, probably due to family reasons or political pressure to reduce the number of women in the workforce. Here, we present a biographical sketch of Ingeborg Beling and review her research on the time memory of honeybees. Furthermore, we discuss the significance of her work, considering what is known about time memory today — nearly 100 years after she conducted her experiments. 

Abstract The Journal of Comparative Physiology A was founded in 1924 as theZeitschrift für vergleichende Physiologieby Karl von Frisch and Alfred Kühn. Given the marginalization of women in science at that time, it is remarkable that the first article in the Journal was authored by a female scientist, Ruth Beutler. Throughout her scientific career, she was affiliated with the Zoological Institute of the University of Munich, which, under the leadership of von Frisch, evolved into a world-class academic institution. Despite chronic health problems, Beutler was one of the first women who succeeded in obtaining theHabilitationas qualification for appointment to a professorial position. She was also one of the first scientists who applied methods from physiological chemistry to the study of zoological phenomena. Yet, for many years she was employed as a technician only, and she was never appointed to anOrdinarius(tenured full professorship) position. Her most important contributions to comparative physiology outside her own area of research were her support for, and protection of, Karl von Frisch, particularly during the Nazi era when he, as a ‘quarter-Jew,’ faced imminent threat of forced retirement; and after World War II, when her efforts as interimOrdinariuswere instrumental in re-building the bombed-out Zoological Institute to persuade Karl von Frisch to return to Munich. It was also one of her observations that prompted him to revisit, and revise, his earlier (incorrect) model of how honeybees communicate, through their dances, the direction and distances of food sources from the hive. 

Abstract Karl von Frisch, one of the leading zoologists of the twentieth century and co-founder of the Journal of Comparative Physiology A, has been frequently portrayed as an opponent of the Nazi regime because he, as a ‘quarter-Jew,’ faced the threat of forced retirement from his position as a professor at the University of Munich during the Third Reich. However, doubts about an active opposition role have surfaced in recent years. A litmus test for assessing the validity of this notion is provided by our discovery that four of the six core members of the anti-Nazi resistance group ‘White Rose’—Sophie Scholl, Hans Scholl, Christoph Probst, and Alexander Schmorell—were his students. When they were arrested, sentenced to death, and executed, he seemed to ignore this historic event, both during and after World War II—in line with his belief that resistance leads to self-destruction, and research can flourish only by ignoring what happens around oneself. On the other hand, this seemingly apolitical attitude did not prevent him from making use of politics when it served his interests. Such actions included his (pseudo-)scientific justification of forced sterilization of people suffering from hereditary disorders during the Third Reich and his praise of the Nazi government’s efforts to “keep races pure.” As unsettling as these and some other political views and actions of Karl von Frisch are, they enabled him to carry out several critical pieces of his research agenda during the Third Reich, which three decades later earned him a Nobel Prize. 

Abstract Eugenol, the major active ingredient of clove oil, is widely used for anesthesia in fish. Yet virtually nothing is known about its effects on CNS functions, and thus about potential interference with neurophysiological experimentation. To address this issue, we employed a neuro-behavioral assay recently developed for testing of water-soluble anesthetic agents. The unique feature of thisin-vivotool is that it utilizes a readily accessible behavior, the electric organ discharge (EOD), as a proxy of the neural activity generated by a brainstem oscillator, the pacemaker nucleus, in the weakly electric fishApteronotus leptorhynchus. A deep state of anesthesia, as assessed by the cessation of locomotor activity, was induced within less than 3 min at concentrations of 30–60 µL/L eugenol. This change in locomotor activity was paralleled by a dose-dependent, pronounced decrease in EOD frequency. After removal of the fish from the anesthetic solution, the frequency returned to baseline levels within 30 min. Eugenol also led to a significant increase in the rate of ‘chirps,’ specific amplitude/frequency modulations of the EOD, during the 30 min after the fish’s exposure to the anesthetic. At 60 µL/L, eugenol induced a collapse of the EOD amplitude after about 3.5 min in half of the fish tested. The results of our study indicate strong effects of eugenol on CNS functions. We hypothesize that these effects are mediated by the established pharmacological activity of eugenol to block the generation of action potentials and to reduce the excitability of neurons; as well as to potentiate GABA_A-receptor responses. 

Abstract A frequent complaint of editors of scientific journals is that it has become increasingly difficult to find reviewers for evaluating submitted manuscripts. Such claims are, most commonly, based on anecdotal evidence. To gain more insight grounded on empirical evidence, editorial data of manuscripts submitted for publication to the Journal of Comparative Physiology A between 2014 and 2021 were analyzed. No evidence was found that more invitations were necessary over time to get manuscripts reviewed; that the reviewer’s response time after invitation increased; that the number of reviewers who completed their reports, relative to the number of reviewers who had agreed to review a manuscript, decreased; and that the recommendation behavior of reviewers changed. The only significant trend observed was among reviewers who completed their reports later than agreed. The average number of days that these reviewers submitted their evaluations roughly doubled over the period analyzed. By contrast, neither the proportion of late vs. early reviews, nor the time for completing the reviews among the punctual reviewers, changed. Comparison with editorial data from other journals suggests that journals that serve a smaller community of readers and authors, and whose editors themselves contact potential reviewers, perform better in terms of reviewer recruitment and performance than journals that receive large numbers of submissions and use editorial assistants for sending invitations to potential reviewers. 

Abstract Curiosity-driven research is fundamental for neuroethology and depends crucially on governmental funding. Here, we highlight similarities and differences in funding of curiosity-driven research across countries by comparing two major funding agencies—the National Science Foundation (NSF) in the United States and the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG). We interviewed representatives from each of the two agencies, focusing on general funding trends, levels of young investigator support, career-life balance, and international collaborations. While our analysis revealed a negative trend in NSF funding of biological research, including curiosity-driven research, German researchers in these areas have benefited from a robust positive trend in DFG funding. The main reason for the decrease in curiosity-driven research in the US is that the NSF has only partially been able to compensate for the funding gap resulting from the National Institutes of Health restricting their support to biomedical research using select model organisms. Notwithstanding some differences in funding programs, particularly those relevant for scientists in the postdoctoral phase, both the NSF and DFG clearly support curiosity-driven research.